Conversion of hydrocarbons with platinum composite catalyst



Patented July 8, 1952 CONVERSION OF HYDROCARBONS WITH PLATINUM COMPOSITECATALYST Vladimir Haensel, Hinsdale, Ill., asslgnor to Universo-l OilProducts Company, Chicago, Ill., a corporation of Delaware No Drawing.Application May 27, 1949, Serial No. 95,883

18 Claims.

This invention relates to the conversion of hydrocarbons and to thepreparation and use of a novel catalyst in the conversion ofhydrocarbons.

In conversion processes of the type wherein carbon formation is a matterof great concern, the commercial success of the process in many casesdepends upon the characteristics of the catalyst to minimize carbonformation but at the same time effect the desired conversion. Typicalexamples of pertinent processes include those in which cracking ofcarbon to carbon bonds occurs as, for example, in the cracking of higherboiling oils or gases to produce lower boiling products, either in thepresence or absence of hydrogen. When hydrogen is present in thecracking operation, the process is generally referred to ashydrocracking.

Another process in which the formation of carbon is of considerableconcern is the reforming process which is effected either in thepresence or absence of hydrogen. In this process the desired reactionsinclude dehydrogenation, isomerization, hydrogen transfer, etc. and acontrolled amount of cracking. As will hereinafter be set forth indetail the amount of cracking must be controlled both in quantity and inquality. However, it has been found that along with cracking theformation of carbon likewise occurs. The deposition of carbon on thecatalyst is undesirable because it inactivates the catalyst andinterferes with the desired conversion.

The carbonaceous deposit on the catalyst includes compounds of carbonand hydrogen and, in the interest of simplicity, is being referred to inthe present specification and claims as carbon. The present invention isdirected to a novel catalyst composition which will minimize theformation of carbon on the catalyst, and to the use of this catalyst inthe conversion of hydrocarbons.

In one embodiment the present invention relates to a conversion processwhich comprises subjecting a hydrocarbon to conversion in the presenceof a catalyst comprising alumina, platinum, combined halogen and notmore than about 1% by weight of an oxide of the group consisting of analkaline earth metal or magnesium.

In a specific embodiment the present invention relates to a process forthe reforming of a gasoline fraction which comprises subjecting saidgasoline fraction to contact at reforming conditions with a catalystcomprising alumina, combined halogen in an amount of from about 0.1% toabout 8% by weight, platinum in an amount of from about 0.01% to about1% by weight, and an alkaline earth metal or magnesium in an amount offrom about 0.01% to about 1% by weight.

In another specific embodiment the present invention relates to a methodof manufacturing a catalyst which comprises precipitating alumina fromaluminum chloride, washing to substantially remove soluble impurities,commingling a halogen therewith, compositing platinum therewith, andcommingling an alkaline earth metal or magnesium compound with thecomposite.

As hereinbefore set forth, in the reforming operation, a controlledamount of hydrocracking is desired, along with the dehydrogenation ofnaphthenic hydrocarbons to produce aromatics, the cyclization of thestraight chain paraflinic hydrocarbons to form aromatics, theisomerlzation of straight chain aliphatic hydrocarbons, hydrogentransfer reactions, etc. The cracking or splitting of carbon to carbonbonds must be controlled both in quantity and in quality. It has beenfound that the selected cracking results in improved reformed products.The lower molecular weight hydrocarbons have higher octane numbers, andalso when the gasoline charging stock contains components boiling aboveabout 400 F., the higher boiling components are cracked to lower boilingcomponents. The overall results of the selective cracking is a reformateof improved properties. However, the cracking must be controlled inquantity so as not to produce an excess of normally gaseous productswhich can not be used in the reformate and, therefore, would result inlower reformate yields. Excessive cracking also results in the formationof larger carbon deposits on the catalyst.

It has been found that a particularly suitable catalyst for use inreforming operations comprises alumina, platinum and combined halogen inspecific amounts. The use of platinum-containing catalyst has been oflimited commercial acceptance because of the high cost of platinum. Ithas been found that exceptionally good catalysts containing smallamounts of platinum may be made in accordance with the presentinvention. The amount of platinum is generally within the range of fromabout 0.01% to about 1% by weight, although in some cases it may rangeup to about 10% by weight of the alumina. The presence of the combinedhalogen in an amount ranging from about 0.1% to about 8% by weightenhances the activity and life of the catalyst. When the halogencomprises fluorine, it is present in an amount of from about 0.1% toabout 3% by weight and when the catalyst comprises chlorine, it ispresent in an amount of from about 0.2% to about 8% by weight. In somecases, the halogen may comprise a mixture of fluorine and chlorine, thetotal thereof being within the range of from about 0.1% to about 8% byweight of the alumina.

erally washed to remove soluble It has been found that the presence ofan alkaline earth metal or magnesium compound serves to reduce theamount of carbon formed during the reforming operation. f the alkalineearth metal compounds, the oxides of calcium, strontium and barium arepreferred. Magnesium has many properties which resemble those of thealkaline earth metals and in many cases has been loosely referred to asan alkaline earth metal. In some cases it has been listed in periodictable arrangements in the left hand column of Group II along with thealkaline earth metals. For example, see The Physical Basis of Things,page 96, by J. A. Eldridge. In the present invention magnesium has shownthe same properties as the alkaline earth metals in reducing carbonformation and, therefore, it is being included in a Markush grouping inthe claims of the present application.

In order to obtain improved results with the low platinumconcentrations, it has been found that alumina shows unexpectedadvantage for use in the catalyst composite. The alumina apparentlyenters into some peculiar association, either chemical or physical, withthe platinum and/or halogen. The exact state of the platinum in thecatalyst composite is not completely established but is believed to be,at least in part, in a combined state with the alumina and/or halogen.However, it is understood that the platinum, at least at some timeduring preparation or use, may be present as free platinum, and the useof the term platinum is intended to include both the combined platinumand the free platinum. Similarly, it is believed that the alkaline earthmetal or magnesium may be present either as the free metal or as a.compound, particularly oxide, which may be associated with the othercomponents of the catalyst, either chemically or physically.

The catalyst of the present, invention may be prepared in any suitablemanner. The alumina is preferably prepared by adding a suitable reagent,such as ammonium hydroxide, ammonium carbonate, etc. to a salt ofaluminum such as aluminum chloride, aluminum nitrate, aluminum acetate.etc. in an amount to form aluminum hydroxide which upon drying isconverted to alumina and, in the interest of simplicity, the aluminumhydroxide is referred to as alumina in the present specification andclaims in order that the percentages are based on the alumina free ofcombined water. It has been found that aluminum chloride is generallypreferred as aluminum salt, not only for convenience in subsequentwashing and filtering procedures, but also because it appears to givebest results.

After the alumina has been formed, it is genimpurities. Usual washingprocedures comprise washing with Water, either in combination withfiltration or as separate steps. It has been found that filtration ofthe alumina is improved when the Wash water includes a small amount ofammonium hydroxide. The severity of the washing may vary. depending uponwhether all or part of the chlorine is to be retained in the catalystcomposite. When chlorine is not desired, the alumina is washedthoroughly to remove substantially all of the chlorine. On the otherhand, if a part of the chlorine is to be retained in the catalyst, thewashing is less severe. In general, it is preferred to wash the aluminathoroughly and, if it is desired to add chlorine, it is added as aseparate step because better control of the amount of the chlorine isobtained in this manner.

The alumina so prepared may be dried, and formed into particles ofuniform or irregular size and shape prior to the addition of the othercomponents, or all or a portion of the other components may be added,and the catalyst subsequently formed into particles. In a preferredembodiment the halogen is incorporated into the alumina before forminginto particles, and this may be accomplished by adding the halogen inthe form of an acid such as hydrogen fluoride, hydrogen chloride.hydrogen bromide and/or hydrogen iodide. In some cases, the volatilesalts such as ammonium fluoride, ammonium chloride. etc. may beemployed. In any event, the amount of halogen will be within the rangehereinbefore set forth.

The platinum may be added to the alumina either before or after thealumina is formed in the particles and either before or after thehalogen or other components are commingled therewith. A hereinbefore setforth, the preferred method is to add the halogen to the alumina. forminto particles, and then add the platinum. In this method the platinumis preferably added in the presence of ammonium hydroxide. Aparticularly preferred method is to commingle chloroplatinic acid withammonium hydroxide to form a mixture having a pH within the range offrom about 5 to about 10 and preferably from about 8 to about 10, andthen commlngle this mixture with the preformed particles. It isunderstood that the ammonium hydroxide or platinum compound first may beadded to the preformed particles and then the other component may beadded, and also that these components may be composited either as coldor hot solutions.

In another embodiment of the invention and particularly when theplatinum is added to the alumina, with or Without halogen, prior toforming the same into particles of uniform size and shape, a preferredmethod is to form a. separate solution of chloroplatinic acid andhydrogen sulfide, and then to utilize this solution for impreghating thealumina.

The use of ammonium hydroxide when adding the platinum compound to thepreformed pills or the use of the chloroplatinic acid-hydrogen sulfidemixture when adding the platinum com pound to the wet alumina-halogencomposite is definitely advantageous in order to obtain evendistribution of the platinum throughout the catalyst. Regardless of themethod of compositing the platinum, it is understood that the amount ofplatinum in the final catalyst will be within the range hereinbefore setforth.

The alkaline earth metal or magnesium compound may be added eitherbefore or after the other components and either before or after all or apart of the catalyst composition has been formed into particles ofuniform size and shape. In general. it is preferred to add the alkalineearth metal or magnesium after the washing and filtration step in orderthat these compounds will not be removed. Thus, the alkaline earth metalor magnesium is preferably added during the final stages or catalystpreparation.

The alkaline earth metal or magnesium may be added in any suitablemanner and usually will be added in the form of a compound which alldecompose on heating to form the oxide. Thus, these compounds may beadded in the form of the nitrate. hydroxide, acetate, etc. Usually thealkaline earth metal or magnesium compound will be added in the form ofan aqueous solution in order to effect uniform distribution on thesurface and within the interior of the catalyst particles. However, itis understood that any other suitable method of intimately disposingthese components within the catalyst may be employed. As hereinbeforeset forth, it is an essential feature of the present invention that theamount of the alkaline earth metal or magnesium compound, determined ascalcium, strontium, barium, magnesium, etc. must not exceed 1% by weightof the alumina. While the use of these compounds in amounts of less than1% by weight and generally within the range of from about 0.01% to about1% by weight will serve to minimize carbon formation without adverselyaffecting the activity of the catalyst, the use of these compounds inamounts greater than 1% will exert a harmful effect on the activity ofthe catalyst and will serve to reduce the desired conversion.

Regardless of when the composite is to be formed into particles ofuniform size and shape, this is readily accomplished by partially dryingat a temperature of from about 200 to about 500 F. for a period of about2 to 24 hours or more to form a cake. A suitable lubricant such asstearic acid, rosin, hydrogenated coconut oil, graphite, etc., is addedto the dried and ground cake and the composite is formed into pills ofuniform size and shape in any suitable pelleting apparatus. The pillsmay range from a size of about 1 x to x A" or more. Pills of uniformsize and shape also may be formed by extrusion methods. When desired,the catalyst may be formed into particles of irregular size and shape bygrinding. When the pills are formed prior to the addition of theplatinum, the pills preferably are calcined in air at a temperature offrom about 1000" to about 1400" F. for a period of from 1 to 8 hours ormore. However, after the platinum has been composited with the alumina,the catalyst should not be calcined at a temperature above about 1000 F.and preferably is calcined in air at a temperature of from about 500 toabout 1000 F. for a period of about 2 to 12 hours or more. In oneembodiment of the invention the catalyst may be reduced in the presenceof hydrogen at a temperature of below about 1000 F. for a period ofabout 2 to 12 hours or more and then calcined in the presence of air ata temperature of from about 500 to about 1000 F. for a period of about 2to 12 hours or more.

It is a particular feature of the present invention that the novelcatalyst composite will reduce carbon formation and, therefore, thecatalyst will have a long life. However, after long periods of service,it may be necessary to regenerate the catalyst and this may beaccomplished by treatment with air or other oxygen containing gas toburn the carbonaceous deposit therefrom. In general, it is preferred tocontrol the regeneration temperature not to exceed about 1000 F. andpreferably the regeneration is effected at a temperature within therange of from about 600 to about 900 F.

The conditions of operation for effecting the conversion of hydrocarbonswill depend upon the particular reactions desired. Reforming of gasolinewill be effected at a temperature of from about 600 to about 1000 F., apressure within the range of from about 50 to about 1000 pounds persquare inch and at a weight hourly space velocity of from about 0.5 toabout 10. The weight hourly space velocity is defined as the weight ofoil per hour per weight of catalyst in the reaction zone. The reformingoperation is preferably effected in the presence of hydrogen and theamount of hydrogen present in the reaction zone generally will be Withinthe range-of from about 0.5 to about 10 mols of hydrogen per mol ofhydrocarbon. The reforming process will be operated under conditions toproduce hydrogen so that the hydrogen so produced may be recycled withinthe process and thus obviate the necessity of introducing hydrogen froman extraneous source except at the start of the process.

It is understood that the reforming process is applicable for thetreatment of a full boiling range gasoline or any selected fractionthereof, and that reference to a gasoline fraction in the presentspecifications and claims is intended to mean either the full boilingrange gasoline or any selected fraction thereof.

As hereinbefore set forth, the catalyst of the present invention is alsoparticularly suitable for use in hydrocracking reactions and these aregenerally effected at temperatures of from about 500 to about 900 F. Thecatalyst of the present invention may also find utility in effectingdehydrogenation reactions and will be utilized in such operations attemperatures of from about 800 to about 1000 F.

The process of the present invention may be effected in any suitableequipment. A particularly suitable process comprises the fixed bedsystem in which the catalyst is disposed in a reaction zone and thehydrocarbons to be treated are passed therethrough in either upward ordownward flow. The products are fractionated to separate hydrogen and torecover the desired products. As hereinbefore set forth, the hydrogen ispreferably recycled for further use in the process. Other suitable unitsin which the process may be effected include the fluidized type processin which the hydrocarbons and catalyst are maintained in a state ofturbulence under hindered settling conditions in a reaction zone, thecompact moving bed process in which the catalyst and hydrocarbons arepassed either concurrently or counter-currently to each other, and thesuspensoid process in which the catalyst is carried into the reactionzone as a slurry in the hydrocarbon oil.

The following examples are introduced to 11- lustrate further thenovelty and utility of the present invention but not with the intentionof unduly limiting the same.

EXAMPLE I Catalyst No. 1 was prepared by adding ammonium hydroxide toaluminum chloride to precipitate aluminum hydroxide. The aluminumhydroxide was washed with ammoniated water. Hydrogen fluoride was addedto the wet alumina in an amount to form a final catalyst containing0.75% of fluorine by weight. A colloidal suspension of chloroplatinicacid and hydrogen sulfide was separately prepared and was added to thealuminum hydroxide-fluorine composite in an amount to form a finalcatalyst containing 0.3% of platinum by weight. The composite was dried,ground into granules and calcined at a temperature of 932 F. for 3hours.

Catalyst No. 2 was prepared in substantially the same manner as catalystNo. 1 except that subseouent to the addition of the colloidal solutionof chloroplatinic acid and hydrogen sulfide and prior to drying, calciumnitrate was added in an amount of 0.1% by weight of calcium based on thealumina. The catalyst was then dried and calcined as set forth in thepreparation of catalyst No. 1.

These catalysts each were separately used in the reforming of aMid-Continent naphtha having a boiling range from 182 to 402 F. Thereforming was effected at a temperature of 851 F. catalyst temperature,a pressure of 500 pounds per square inch, a weight hourly space velocityof 2 and a hydrogenzhydrocarbon ratio of 3:1. Each of the runs wasconducted for 3 days, and the results of the third day of operation areshown in the following table, along with additional analysis of thecharging stock.

It will be noted from the data in the above table that catalyst No. 2containing 0.1% of calcium produced only 0.76% by weight of carbon, ascompared to a value of 2.46% of carbon for the catalyst No. 1 notcontaining calcium.

EXAMPLE II Catalyst No. 3 was prepared by adding ammonium hydroxide toaluminum chloride to precipitate aluminum hydroxide, washing to removesoluble impurities, adding hydrogen fluoride in an amount to form afinal catalyst containing 0.3% fluorine, drying, pilling and calciningthe composite. Chloroplatinic acid-ammonium hydroxide solution was addedto the pills to form a final catalyst containing 0.3% platinum,following which the catalyst was calcined at a temperature of 932 F. for3 hours.

Catalyst No. 4 was prepared in substantially the same manner as catalystNo. 3 except that subsequent to the addition of the chloroplatinicacids, magnesium nitrate was added in an amount to form a final catalystcontaining 0.1% magnesium oxide and the catalyst then was calcined inthe same manner as catalyst No. 3.

' These catalysts were separately used for the reforming of aMid-Continent naphtha having a boiling range of 182 F. to 402 F., amotor method octane number of 34.6, a research method octane number of34.8, and 2. Reid vapor pressure of 1.0 pound. The reforming waseffected at a temperature of 850 F. catalyst temperature, pressure of500 pounds per square inch, a weight hourly space velocity of 2, and ahydrogenzhydrocarbon ratio of 3:1. Here again the runs were continuedfor 3 days. The results of the third day operation are shown in thefollowing table.

Table II It will be noted that the catalyst containing magnesium oxideproduced about 20% less carbon than was produced with a catalyst notcontaining magnesium.

From the data in Tables I and II, it is noted that the amount of carbonformed during the reforming operation is reduced. This reduction incarbon is very important from a commercial view point because it meansthat the process may continue for much longer periods of time beforeregeneration or replacement of the catalyst. This of course is importanteconomically because it means that operation of the process does nothave to be discontinued to regenerate or replace the catalyst asfrequently as otherwise would be necessary and also the cost, both inmanpower and equipment, of regenerating the catalyst is reduced.

I claim as my invention:

1. A conversion process which comprises subjecting a hydrocarbon toconversion in the presence of a catalyst comprising alumina, platinum,combined halogen and not more than about 1% by weight of an oxide of thegroup consisting of an alkaline earth metal and magnesium.

2. A conversion process which comprises subjecting a hydrocarbon toconversion in the presence of a catalyst comprising alumina, from about0.01% to about 1% by weight of platinum, from about 0.1% to about 8% byweight of combined halogen and from about 0.01% to about 1% by weight ofan oxide of the group consisting of an alkaline earth metal andmagnesium.

3. A process for reforming a gasoline fraction which comprisessubjecting said fraction to contact at reforming conditions with acatalyst comprising alumina, platinum, combined halogen and not morethan about 1% by weight of calcium oxide.

4. A process for reforming a gasoline fraction which comprisessubjecting said fraction to contact at reforming conditions with acatalyst comprising alumina, platinum, combined halogen and not morethan about 1% by weight of magnesium oxide.

5. A process for the reforming of a gasoline fraction which comprisessubjecting said fraction to reforming at reforming conditions in thepresence of a catalyst comprising alumina, from about 0.01% to about 1%by weight of platinum, from about 0.1% to about 8% by weight of combinedhalogen and from about 0.01% to about 1% by weight of an oxide of thegroup consisting of an alkaline earth metal and magnesium.

6. The process of claim 5 further characterized in that said halogencomprises fluorine in an amount 01 from about 0.1% to about 3% byweight.

7. The process of claim 5 further characterized in that said halogencomprises chlorine in an amount of from about 0.2% to about 8% byweight.

8. The process of claim 5 further characterized in that said oxidecomprises calcium oxide.

9. The process of claim 5 further characterized in that said oxidecomprises magnesium oxide.

10. A method of preparing a catalyst which comprises combining a halogenwith alumina, compositing platinum therewith, commingling an oxide ofthe group consisting of an alkaline earth metal and magnesium therewithin an amount not more than about 1% by weight of the composite, andcalcining the composite.

11. A method of manufacturing a catalyst which comprises combiningfluorine with alumiha in an amount of from about 0.1% to about 3% byweight of said alumina on a dry basis, thereafter commingling therewithplatinum in an amount of from about 0.01% to about 1% by weight andcalcium oxide in an amount of from about 0.01% to about 1% by weight,and calcining the resultant composite.

12. A method of manufacturing a catalyst which comprises combiningfluorine with alumina in an amount of from about 0.1% to about 3% byweight of said alumina on a dry basis. thereafter commingling therewithplatinum in an amount of from about 0.01% to about 1% by weight andmagnesium oxide in an amount of from about 0.01% to about 1% by weight,and calcining the resultant composite.

13. A method of manufacturing a catalyst which comprises compositingfluorine with alumina in an amount of from about 0.1% to about 3% byweight of said alumina on a dry basis, drying said alumina-fluorinecomposite and forming the same into particles of uniform size and shape,thereafter commingling therewith platinum in an amount of from about0.01% to about 1% by weight and calcium oxide in an amount of from about0.01% to about 1% by weight, and calcining the resultant composite.

14. A method of manufacturing a catalyst which comprises compositingchlorine with alumine in an amount of from about 0.2% to about 8% byweight of said alumina on a dry basis, drying said alumina-chlorinecomposite and forming the same into particles of uniform size and shape,thereafter commingling therewith platinum in an amount of from about0.01% to 10 about 1% by weight and magnesium oxide in an amount of fromabout 0.01% to about 1% by weight, and calcining the resultantcomposite.

15. A catalyst comprising alumina. from about 0.01% to about 10% byweight of platinum, from about 0.1% to about 8% by weight of an oxideselected from the group consisting of the alkaline earth metal oxidesand magnesia.

16. A catalyst comprising alumina, from about 0.01% to about 1% byweight of platinum, from about 0.1% to about 3% by weight of combinedfluorine, and from about 0.01% to about 1% by weight of an oxideselected from the group consisting of the alkaline earth metal oxidesand magnesia.

1'7. A catalyst comprising alumina, from about 0.01% to about 1% byweight of platinum, from about 0.1% to about 3% by weight of combinedfluorine, and from about 0.01% to about 1% by weight of calcium oxide.

18. A catalyst comprising alumina, from about 0.01% to about 1% byweight of platinum, from about 0.1% to about 3% by weight of combinedfluorine, and from about 0.01% to about 1% by weight of magnesium oxide.

VLADIMIR HAENSEL.

REFERENCES CITED UNITED STATES PATENTS Name Date Haensel Aug. 16, 1949Number

5. A PROCESS FOR THE REFORMING OF A GASOLINE FRACTION WHICH COMPRISESSUBJECTING SAID FRACTION TO REFORMING AT REFORMING CONDITIONS IN THEPRESENCE OF A CATALYST COMPRISING ALUMINA, FROM ABOUT 0.01% TO ABOUT 1%BY WEIGHT OF PLATINUM, FROM ABOUT 0.1% TO ABOUT 8% BY WEIGHT OF COMBINEDHALOGEN AND FROM ABOUT 0.01% TO ABOUT 1% BY WEIGHT OF AN OXIDE OF THEGROUP CONSISTING OF AN ALKALINE EARTH METAL AND MAGNESIUM.